1. Using Mobility Support for Request-Routing in IPv6 CDNs Arup Acharya and Anees Shaikh TJ Watson Research Center Presented by Renu Tewari

2. Request-Routing in CDNs zRR directs client HTTP requests to “proximal” server yIn IPv4 CDNs, RR primarily via DNS zKey observation: RR is congruent to IP mobility yuse mobile IP mechanisms for redirection yno need to overload DNS zIn IPv4, mobility requires deployment of “mobility agents” yexisting hosts remain unchanged yhowever, all packets routed via home agent  triangular routing zIPv6 offers native mobility support ysupport present in any IPv6 node ydirect routing between mobiles and correspondents èRR can use mobility mechanisms without modification

3. DNS Request Routing (IPv4) client local ns root nameserver www.abc.com? ns.abc.com (TTL = 1d) www.abc.com? 12.100.104.5 (TTL = 0) 12.100.104.5 63.64.105.4 12.100.104.5 CDN servers modified nameserver

4. origin server client DNS server www.abc.com? local NS IP V CDN servers IPv6 RR (IP V ) RR in IPv6 using mobility support yresolve name to an IP address (IP v )

5. client (IP C ) IPv6 RR (IP V ) dest: IP V src: IP C TCP SYN f (IP C, IP V ) = IP L CDN server (IP L ) TCP SYN IPv6 Request-Routing (cont.) yRR chooses proximal server (IP L ) correspondent node home agent mobile node yforwards SYN pkt to IP L in IP-in-IP tunnel

6. client (IP C ) IPv6 RR (IP V ) CDN server (IP L ) SYN/ACK HA: IP V dest: IP C src: IP L bind upd IP V IP L binding cache TCP SYN dest: IP V src: IP C IPv6 Request-Routing (cont.) zCDN server sends IP v  IP L mapping to client via a binding update, piggybacked on SYN/ACK zclient creates binding cache entry

7. client (IP C ) IPv6 RR (IP V ) CDN server (IP L ) IP V IP L binding cache HTTP GET RH: IP V dest: IP L src: IP C IPv6 Request-Routing (cont.) ysubsequent client pkts sent to IP L (IP v placed in routing header) yTCP endpoint:

8. Additional remarks zIPv6 mobility provides an alternate mechanism for RR yRR policies and metrics must be implemented at the home agent zFunctionality similar to DNS, without some problems yIPv6 RR sees actual client address – improved accuracy yCDN server can use lifetime field in binding cache to control duration of binding zTake advantage of large address space in IPv6 ymap CDN customers to distinct (virtual) IP addresses yuse additional addresses for granular content-based-routing (e.g., streaming, images, etc.)

9. xcorrespondents always send pkts via home agent xhome agent is in forward data path xhome agent tunnels pkts to mobile xmobile can respond directly to correspondent home agent mobile node correspondent mobility agents

10. zFor a home agent to function as a req-router yRequire load info about each CDN server, or yA knowledgebase correlating IP addresses with topology/geography: match client and proximal servers

12. client CDN B CDN server RR A RR B CDN A Content Internetworking